Re: Love, Necessity and Pride
Notes and ramblings on an old timetable...
This going to get ugly, so unless you have nothing better to do, I recommend skipping the following incoherent jibberish of a doofus...
...
You have been warned...
Been doin some wondering on MEKP to resin ratios...
At my local supplier, they include 1 ounce of MEKP for one Gallon of resin...
Here on Iboats we are usually using the metric system to come up with our ratios...
So, using the metric system...100ml of resin, takes 1ml of catalyst...etc...etc...200/2, 300/3...this is at 1%cat to resin...obviously, double that cat for 2%...
So if I convert one gallon of resin to ml's, I get 3785.41178 ml in one U.S. Gallon, that is, provided the gallon of resin actually weighs 128 Ounces...One ounce is equal to 29.5735 ml, again MEKP may have a different liquid weight/specific gravity than an ounce of water...
Now I am getting confused here, but stay with me while I work this out...
If 1 Gal.=3785ml's[rounded for clarity]and is =128 ounces...
then by my reckoning, if 1oz. of catalyst is used per gallon...the pro shops down here are using approximately a .75% cat ratio for the resin...maybe even less if the actual weight of a gallon of this particular resin is actually more than a US gallon of water...which it may well be...
Because if they were using the 1% ratio, you should be recieving approximately 38ml of catalyst for every gallon which works out to about 1.7oz of MEK-P...or even 3.4 ounces of MEKP to do a 2% cat ratio...but that would only apply if the actual the gallon of resin weighed 128 ounces...which they don't necessarily and can vary quite alot depending on the chemical make-up of the resin...which helps to clear up why I have gone through so much catalyst...
I am using between 1% and 2% cat ratio...which at that rate is about double the amount they use in boat fabrication down here...
Just for comparison, USComposites has this info available for their 404 resin...139.84/4136ml-153.12/4528ml ounces in a gallon of poly resin from USC and they provide 2oz/76ml of MEKP for each gallon...51.7ml-56.6ml MEKP used @ 1.25% ratio...given their numbers they provide enough catalyst for up to a 1.75% ratio using the heavy gallon number of 4528ml per gal...
Is anybody still following along at this point...
I am not saying anything by this other than trying to figure out why I did not have enough MEK-P for all of the resin and now, after doing some math, I understand why...
There doesn't seem to be any hard and fast rules regarding this subject, other than going by what the specific provider of the specific product recommends, which also, does not seem to be always etched in stone...:facepalm:
The other reason I put this in my thread is to help any who might be encountering the same thing understand this discrepancy...
Maybe the professional boat building yards know something we don't, or maybe they are just building future restorations for Iboats members...either way I have also read of very hot climate boat restorers using as little as .7% or less, cat ratio with complete success and vice versa, cold weather folks going as high as 3%-4%...
I don't claim to actually know what I am talking about most of the time, but this sure is confusing...I guess there is reams and reams of scientific data to prove or disprove whether or not this is really an issue when it comes to the final strength of resin, but my brain is beginning to hurt from all this thinking and will now gladly return you to our regularly scheduled program...
Happy Monday and Carry on...
PS- this is what happens when its raining and I can't get any work done on the boat and I am still waiting for the MBS phone call...:redface:
